Adhesive composition poly(vinyl alkyl ether) and a cyclic ester polymer

ABSTRACT

COMPOSITE ARTICLES HAVING AT LEAST ONE SOLID SUBSTRATE OF SUCH DIVERSE NATURE AS GLASS, LEATHER, CELLULOSIC SOLIDS (INCLUDING WOOD, PAPER, COTTON AND CELLULOSE DERIVATIVES), POLYAMIDE SOLIDS, POLYURETHANE SOLIDS, NATURAL RUBBER SOLIDS, SYNTHETIC RUBBER SOLIDS, PHENOLIC RESIN SOLIDS, EPOXY RESIN SOLIDS, STYRENE POLYMER AND COPOLYMER SOLIDS AND THE LIKE, BONDED TO AN ADHESIVE BODY WHICH IS ANTI-BLOCKING (NON-TACKY) AT AMBIENT TEMPERATURE BUT IS HEAT ACTIVATABLE AT RELATIVELY MODERATE TEMPERATURE AS LOW AS 60* C. TO PROVIDE EXCELLENT BONDING UPON COOLING TO AMBIENT TEMPERTURES, AND WHICH COMPRISES A CYCLIC ESTER POLYMER HAVING RECURRING UNITS OF THE FORMULA:   -(O-(C(-R)2)X-(A)Z-(C(-R)2)Y-CO)-   WHEREIN EACH R, INDIVIDUALLY, IS SELECTED FROM THE CLASS CONSISTING HYDROGEN, ALKYL, HALO, AND ALKOXY; A IS THE OXY GROUP; X IS AN INTEGER FROM 1 TO 4; Y IS AN INTEGER FROM 1 TO 4; Z IS AN INTEGER OF ZERO OR ONE; WHICH THE POVISOS THAT (A) THE SUM OF X+Y+Z IS AT LEAST 4 AND NOT GREATER THAN 7, AND (B) THE TOTAL NUMBER OF R VARIABLES WHICH ARE SUBSTITUENTS OTHER THAN HYDROGEN DOES NOT EXCEED 3, WITH OR WITHOUT RECURRING UNITS OF THE FORMULA:   -(O-CH(-R&#39;&#39;)-CH(-R&#39;&#39;))-   WHEREIN EACH R&#39;&#39; IS SELECTED FROM THE CLASS CONSISTING OF, INDIVIDUALLY, HYDROGEN, ALKYL, CYCLOALKYL, ARYL, AND CHLOROALKYL, AND, TOGETHER WITH THE ETHYLENE MOIETY OF THE OXYETHYLENE CHAIN OF UNIT II, A SATURATED CYCLOALIPHATIC HYDROCARBON RING HAVING 4 TO 8 CARBON ATOMS. ALSO, NOVEL ADHESIVE COMPOSITIONS CONTAINING THE ABOVE-DESCRIBED CYCLIC ESTER POLYMER AND VINYL ALKYL ETHERS IN THE FORM OF SOLUTIONS, DISPERSIONS, POWDERS, FILMS COATING AND GRANULES OR PELLETS. THE INVENTION IS APPLICABLE TO ADHERING A BROAD RANG OF DIVERSE TYPES OF SUBSTRATES WITHOUT THE NECESSITY OF USING HIGH TEMPERATURES OR LONG SETTING TIMES OR TOXIC MATERIALS. IT IS ALSO APPLICABLE TO THE PRODUCTION OF HEAT ACTIVATABLE COATINGS OR SEALS FOR DIVERSE PACKAGING MATERIALS, LAMINATING USES, CONSTRUCTION USES, INVESTMENT MOLDING TYPE CASTINGS, AND REPAIR USES.

United States Patent 3,641,204 ADHESIVE COMPOSITION POLYOVINYL ALKYLETHER) AND A CYCLXC ESTER POLYMER Robert Dean Lnndberg, Somerville,N.J., Joseph Victor Koleske and Dale Flavian Pollart, Charleston, W.Va., and Walter Henry Smarook, Somerville, N..l'., assignors to UnionCarbide Corporation, New York, N.Y. No Drawing. Filed Apr. 1, 1969, Ser.No. 812,320 Int. Cl. C08g 43/02 U.S. Cl. 260-874 5 Claims ABSTRACT OFTHE DISCLOSURE L w. J

wherein each R, individually, is selected from the class consisting ofhydrogen, alkyl, halo, and alkoxy; A is the oxy group; x is an integerfrom 1 to 4; y is an integer from 1 to 4; z is an integer of zero orone; which the provisos that (a) the sum of x+y+z is at least 4 and notgreater than 7, and (b) the tot-a1 number of R variables which aresubstituents other than hydrogen does not exceed 3, with or withoutrecurring units of the formula:

I I an r r n wherein each R is selected from the class consisting of,individually, hydrogen, alkyl, cycloalkyl, aryl, and chloroalkyl, and,together with the ethylene moiety of the oxyethylene chain of unit II, asaturated cycloaliphatic hydrocarbon ring having 4 to 8 carbon atoms.Also, novel adhesive compositions containing the above-described cyclicester polymer and vinyl alkyl ethers in the form of solutions,dispersions, powders, films, coatings and granules or pellets. Theinvention is applicable to adhering a broad range of diverse types ofsubstrates without the necessity of using high temperatures or longsetting times or toxic materials. It is also applicable to theproduction of heat activatable coatings or seals for diverse packagingmaterials, laminating uses, construction uses, investment molding typecastings, and repair uses.

BACKGROUND OF THE INVENTION (a) Field of the invention The presentinvention relates to novel composite articles comprising solidsubstrates of diverse types bonded to adhesive compositions which areheat-activatable at rela tively moderate temperatures and to novelheat-activatable adhesive compositions for use therein. Moreparticularly, the invention relates to composite articles of one or moresolid substrates, or layers of solid substrates, each bonded to theheat-activatable adhesive composition which contain a cyclic esterpolymer as an adhesive component and to novel heat-activatable adhesivecompositions containing cyclic ester polymers and poly(vinyl alkylether).

(13) Description of the prior art There are a great many adhesives knownin the prior art. There are several basic types including the monomericadhesives which must be catalyzed to produce a strong bond, solventadhesives which contain dissolved plastic and depend upon evaporation toform the bond, bodied adhesives which contain thermoplastic orthermosetting resins and solvents with or without plasticizers andrequire evaporation of solvent to form a strong bond, elastomericadhesives based on natural and synthetic rubber and depending on theevaporation of solvent to form a strong bond, reactive adhesives such asthe epoxies or phenolics which depend upon a catalytic reaction toeffect a strong bond, and heat-activatable adhesives such asthermoplastics, e.g., poly(vinyl butyral), which are softened or meltedwhen heated and form strong bonds when cooled.

SUMMARY OF THE INVENTION This invention is directed to novel compositearticles formed of at least one solid substrate bonded to aheatactivatable adhesive composition which is non-tacky andanti-blocking at ambient temperatures of normal use, yet are activatableby heating to moderate temperatures. e. g., as low as 60 C., to formstrong, tough bonds with diverse solid substrates when cooled to ambienttemperatures. The invention is also directed to novel adhesivecompositions suitable for forming the above-mentioned compositearticles. The adhesive compositions used in the production of suchcomposite articles can be in the form of powders, solutions,dispersions, melts, films, tapes, sheets, granules or pellets and thespecific form is dependent on convenience for a particular use and issubject to the choice of the user.

The adhesive compositions used herein can be coated onto the surface ofa solid substrate by a variety of methods as will be described in detailhereinafter to form a heat-activatable coating. The coatings so formedare antiblocking and can be contacted with each other under pressure atambient temperatures for extended periods of time without adhering toeach other. Similarly the solid forms, i.e. powders, granules, pellets,tapes, sheets and films, of the adhesive compositions can be pressurecontacted with each other over long periods at ambient temperatureswithout adhering to each other. Nonetheless, upon heating to moderatetemperatures and pressure contacting with a solid substrate, strong,tough adhesive bonds are formed after cooling. These characteristics ofthe present invention greatly simplify the shipment, storage andhandling of the composite articles and adhesive compositions disclosedherein.

The adhesive compositions in the solid forms as listed above or asbonded to one or more solid substrates are further characterized by ahigh degree of creep resistance at ambient temperatures and thischaracteristic is highly important in the shipment, storage and handlingof the adhesive compositions as well as in the service use of thecomposite articles.

Diverse solid substrates can be bonded to the adhesive composition inthe practice of this invention including cellulosic solids, such aswood, including plywood; paper, both filled and unfilled; cellulosicfibers, fabrics (knitted, Woven and non-woven) and textile productsincluding garments, sheets, pillowcases, draperies, curtains, upholsteryand the like, made of cotton, rayon, blends of cotton and rayon, blendsof cotton or rayon with synthetic fibers, such as, poly(ethyleneterephthalate) fibers, polyacrylonitrile fibers, nylon fibers and thelike, cellulose derivatives such as solid nitrocellulose, solidcellulose ethers, including ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, carboxy methyl cellulose, solid celulose esters, suchas cellulose acetate, cellulose decanoates and the like, glass of alltypes; leather; other natural and synthetic fibers, fabrics (knitted,woven or non-woven) and textile products made of wool fibers, nylonfibers, poly(ethylene terephthalate) fibers, polyacrylonitrile fibersand blends of two or more such fibers, polypeptides, nylons,thermoplastic polyurethanes, polyesters of polycarboxylic acids andpolyhydric alcohols, preferably dicarboxylic acids and dihydricalcohols, the normally solid acrylic polymers and copolymers, such as,poly (methyl methacrylate), poly(ethyl methacrylate),poly(acrylonitrile) and those described on pp. 133 to 138 of ModernPlastics Encyclopedia, 1964 and references cited therein,polycarbonates; polysulfones, styrene polymers and copolymers, such aspolystyrene, styrene-acrylonitrile copolymers, styrenemethylmethacrylate copolymers; polymers and copolymers of olefinicallyunsaturated carboxylic acids and anhydrides; elastomers, such as naturalrubber and synthetic rubbers including butyl rubber, nitrile rubber,polybutadiene rubber, polyisobutylene rubbers,acrylonitrilebutadiene-styrene rubbers, ethylene-propylene terpolymerrubbers, and silicone rubbers; phenolic resins, thermo' setpolyurethanes, epoxy resins, melamine resins, polyureas, ureaformaldehyde condensates; and painted, enameled or lacquered surfaces.No special treatments of the solid substrates are necessary, theirsurfaces should only be reasonably clean and free of dirt, oil or othercontaminants.

The cyclic ester polymers which are contemplated in the practice of theinvention are those which possess a reduced viscosity value of at leastabout 0.3 to about 15, and higher. The preferred polymers of cyclicesters for many applications have a reduced viscosity value of fromabout 0.5 to about 10. These polymers are further characterized by thefollowing recurring structural linear r ra rain l M. \tLJ wherein eachR, individually, is selected from the class consisting of hydrogen,alkyl, halo, and alkoxy; A is the oxy group; x is an integer from 1 to4; y is an integer from 1 to 4; z is an integer of zero or one; with theprovisos that (a) the sum of x+y+z is at least 4 and not greater than 7,and (b) the total number of R variables which are substituents otherthan hydrogen does not exceed 3, preferably does not exceed 2, per unit.Illustrative R variables include methyl, ethyl, isopropyl, n-butyl,secbutyl, t-butyl, hexyl, chloro, bromo, iodo, methoxy, ethoxy,n-butoxy, n-hexoxy, 2-ethylhexoxy, dodecoxy, and the like. It ispreferred that each R, individually, be hydrogen, lower alkyl, e.g.,methyl, ethyl, n-propyl, isobutyl, and/or lower alkoxy, e.g., methoxy,ethoxy, propoxy, nbutoxy, and the like. It is further preferred that thetotal number of carbon atoms in the R substituents does not exceedtwenty.

In one embodiment, highly desirable cyclic ester polymers which arecontemplated are characterized by both recurring structural unit I supraand recurring structural unit II:

R R F 1 l l m L H 1I i wherein each R is selected from the classconsisting of, individually, hydrogen, alkyl, cycloalkyl, aryl, andchloroalkyl, and, together with the ethylene moiety of the oxyethylenechain of unit II, a saturated cycloaliphatic hydrocarbon ring havingfrom 40 to 8 carbon atoms, desirably from 5 to 6 carbon atoms. It ispreferred that recurring unit [I contains from 2 to 12 carbon atoms.Illustrative R variables include methyl, ethyl, n-propyl, isopropyl,t-butyl, the hexyls, the dodecyls, 2-chloroethyl phenyl, phenetyl,ethylephenyl cyclopentyl, cyclohexyl, cycloheptyl, and the like. It ispreferred that R be hydrogen; lower alkyl, e.g., methyl, ethyl,n-propyl, isopropyl; chloroalkyl, e.g., 2-chloroethyl and the like.

The aforedescribed recurring linear unit (I) is interconnected throughthe oxy group (O) of one unit with the carbonyl group of a second unit.In different language, the interconnection of these units does notinvolve the direct bonding of two carbonyl groups, i.e.,

With relation to the relatively high molecular weight cyclic esterpolymers, the terminal moieties thereof are not determinable byinfra-red analysis which factor is readily understandable sincemacromolecules are involved. On the other hand, the relatively lowermolecular weight cyclic ester polymers, e.g., those having reducedviscosity values below about 0.25 are characterized by end groups whichcan be hydroxyl; carboxyl; hydrocarbyl such as alkyl, cycloalkyl, aryl,aralkyl, and alkaryl; hydrocarbyloxy such as alkoxy, cycloalkoxy,aryloxy, aralkoxy, and alkaryloxy; and possibly other moieties such ascatalyst residue; and mixtures of the foregoing. It may be desirable incertain instances that the hydroxyl and carboxyl end groups, if present,he esterified or acylated to render them inert such as by reacting thehydroxyl moiety with a monocarboxyl compound or its correspondinganhydride, e.g., acetic acid, acetic anhydride, butyric acid,2-ethylhexanoic acid, benzoic acid, etc., or by reacting the oarboxylmoiety with a monohydroxyl compound such as a monohydric alcohol ormonohydric phenol, e.g., methanol, 2-ethylhexanol, isobutanol, phenol,and the like.

When the cyclic ester polymers are prepared from a mixture containingthe cyclic ester monomer and minor amounts of a cyclic ether which iscopolymerizable therewith, e. g., alkylene oxide, oxetane,tetrahydrofuran, etc., the polymeric chain of the resulting copolymericproduct will be characterized by both recurring linear unit I supra aswell as the recurring linear unit II which would represent the alkyleneoxide comonomer polymerized therewith. When the comonomer is an alkyleneoxide, then the resulting copolymeric product will contain bothrecurring linear unit I and recurring linear unit II in the copolymericchain thereof. The interconnection of linear unit I and linear unit IIsupra does not involve or result in the direct bonding of two oxygroups, i.e., -OO. In other words, the oxy group (-O-) of recurringlinear unit II is interconnected with the carbonyl group of recurringlinear unit I supra or with the alkylene moiety of a second oxyalkyleneunit II.

Particularly preferred polymers of cyclic esters are those which arecharacterized by the oxypentamethylenecarbonyl chain as seen inrecurring structural unit III:

I .IEIL

L \l./, l

wherein each R is hydrogen or lower alkyl, preferably hydrogen ormethyl, with the proviso that no more than three R variables aresubstituents other than hydrogen.

The preparation of the cyclic ester polymers are Well documented in thepatent literature as exemplified by US. Pat. Nos. 3,021,309 through3,021,317; 3,169,945; 3,274,- 123; 3,305,605; 3,324,070 and 2,962,524and Canadian Pat. No. 742,294. Briefly, the process involves thepolymerization of an admixture containing at least one cyclic estermonomer with or without a functional (e.g., active hydrogen-containing)initiator therefor, and a suitable catalyst, the choices of which willdepend on the presence or absence of added initiator.

Suitable monomeric cyclic esters which can be employed in themanufacture of the cyclic ester polymers are best illustrated by thefollowing formula:

wherein the R, A, x, y, and 2 variables have the significance noted inunit I supra.

Representative monomeric cyclic esters which are contemplated include,for example, delta-valerolactone; epsilon-caprolactone;zeta-enantholactone; eta-caprylolactone; themonoalkyl-delta-valerolactones, e.g., the monomethyl-, monoethyl-,monohexyl-, delta-valerolactones, and the like; thedialikyl-delta-valerolactone's, e.g., the dimethyl-, diethyl-, anddi-n-octyl-delta-valerolactones, and the like; the monoalkyl-dialkyl-,and tri-alkyl-epsilon-caprolactones, e.g., the monomethyl-, monoethyl-,monohexyl-, dimethyl-, diethyl-, di-n-propyl, di-n-hexyl-, trimethyl-,triethyl-, and tri-n-propyl-epsilon-caprolactones, and the like; themonoalkoxyand dia1koxy-delta-valerolactones and epsilon-caprolactones,e.g., the monomethoxy-, monoisopropoxy-, dimethoxy-, anddiethoxy-delta-valerolactones and epsiloncaprolactones, and the like;1,4-dioxane-2-one, dimethyl- 1,4-dioxane-2-one; and the like. A singlecyclic ester monomer or mixtures of such monomers may be employed.

-In the absence of added functional initiator, and polymerizationprocess is desirably effected under the operative conditions and in thepresence of anionic catalysts as noted in U.S. Pat. Nos. 3,201,309 to3,021,317 such as dialkyl- Zinc, dialkylmagnesium, dialkylcadmium,trialkylaluminum, dialkylaluminum alkoxide, alkylaluminum dialkoxide,dialkylaluminum halide, aluminum trialkoxide, alkyllithium, andaryllithium. Specific anionic catalysts would include di-n-butylzinc,diethylmagnesium, di-nbutylmagnesium, dirnethylcadmium, diethylcadmium,dit-butylcadmium, triethylaluminum, triisobutylaluminum, tri 2ethylhexylaluminum, aluminum triisopropoxide, aluminum triethoxide,ethyllithium, n-butyllithium, phenyllithium, and the like.

When employing an admixture containing cyclic ester monomer andfunctional initiator which possesses at least one active hydrogensubstituent, e.g., amino, carboxyl, and hydroxyl, it is desirable to usethe catalysts noted in U.S. Pat. Nos. 2,878,236; 2,890,208; 3,169,945;and 3,284,417 under the operative conditions discussed therein. In theseprocesses the active hydrogen substituent on the initiator is capable ofopening the monomer cyclic ester ring whereby said cyclic ester is addedto said initiator as a substantially linear group thereto. The molecularweight of the resulting polymers of cyclic ester can be predetermined bycontrolling the molar ratios of cyclic ester monomer to be added to thefunctional initiator. Amino and hydroxyl s-ubstituents on the initiatorwill result in polymeric products having hydroxyl end-group. Carboxylsubstituents on the initiator will result in polymeric products havingcarboxyl end-groups. The initiator with the active hydrogen atom willthus be contained in the final polymeric molecule. The esterification oracylation of the aforementioned end-groups has been described previouslyand is voluminuously documented in the art.

Polymers of cyclic esters can also be manufactured via the processdescribed in U.S. Pat. No. 2,962,524. In this process, a monomericadmixture comprising cyclic ester and alkylene oxide which desirably hasthe formula:

wherein each R, individually, have the meanings noted in unit II supra,can be reacted with a monofunctional I and/or polyfunctional (e.g.active hydrogen-containing) initiator possessing amino, hydroxyl and/orcarboxyl groups, preferably in the presence of a Lewis acid catalystsuch as boron trifluoride. Illustrative alkylene oxides would includeethylene oxide, propylene oxide, the butylene oxides, styrene oxide,epichlorohydrin, cyclohexene oxides, and the like.

Cyclic ester/alkylene oxide copolymers can also be prepared by reactingin the absence of an active hydrogencontaining initiator an admixturecomprising cyclic ester and alkylene oxide monomers, an interfacialagent such as a solid, relatively high molecular weight poly(vinylstearate) or lauryl methacrylate/vinyl chloride copolymer (reducedviscosity in cyclohexanone at 30 C. of from about 0.3 to about 1.0), inthe presence of an inert normally-liquid saturated aliphatic hydrocarbonvehicle such as heptane, phosphorous pentafluoride as the catalysttherefor, at an elevated temperature, e.g., about C., and for a periodof time sufficient to produce such cyclic ester/alkylene oxidecopolymers.

The cyclic ester polymers employed herein contain in the polymeric changreater than 50, preferably about 80, to about mol percent of Units Iand about 0 to less than about 50, preferably about 20, mol percent ofother units such as alkylene oxide units II, initiator residues ormoieties, catalyst residues, and other difunctional and/ormonofunctional units. The cyclic ester polymers containing about 100 molpercent of unit I are preferred and those in which unit I represents theoxypentamethylene carbonyl moiety are most preferred.

As mentioned previously, the polymers of cyclic esters which arecontemplated are expressed in terms of their reduced viscosity values.As is well known in the art, reduced viscosity value is a measure orindication of the molecular weight of polymers. The expression reducedviscosity is a value obtained by dividing the specific viscosity by theconcentration of polymer in the solution, the concentration beingmeasured in grams of polymer per 100 milliliters of solvent. Thespecific viscosity is obtained by dividing the difference between theviscosity of the solution and the viscosity of the solvent by theviscosity of the solvent. Unless otherwise noted, the reduced viscosityvalues herein referred to are measured at a concentration of 0.2 gram ofpolymer in 100 milliliters of benzene benzene is preferred althoughcyclohexanone, chloroform, toluene or other organic solvent for thepolymer may be used) at 30 C.

The cyclic ester polymer can be fluxed on a mill and sheeted off to formsheets or films. It can be extruded as a tape, rope, or other shape orcan be extruded and pelletized. When formed by the dispersionpolymerization technique, the cyclic ester polymer is obtained in powderor granular form. It can also be dissolved in a suitable solvent, suchas, benzene, toluene, 2-nitropropane, methylene chloride and othersolvents. Methylene chloride and other fast drying solvents arepreferred when the cyclic ester is applied to the substrate as asolution. The cyclic ester polymer can be employed alone as the adhesivecomposition or can be intimately mixed with poly(vinyl alkyl ether) toform the adhesive composition.

Poly(vinyl alkyl ether) which may be employed in the adhesivecompositions in this invention include poly- (vinyl methyl ether),poly(vinyl ethyl ether), poly(viny1 isobutyl ether), poly(vinyl hexylether), poly(vinyl octyl ether) and the like. Preferably, such polymerscontain no more than about eight carbon atoms in each alkyl groupthereof and each polymeric molecule can contain the same or differentalkyl groups. The vinyl alkyl ether monomers are prepared in any wellknown manner as by the catalytic reaction of acetylene with an alkanolwhich contains the desired alkyl group.

The novel adhesive mixtures disclosed and claimed herein contain fromabout 10, to about 90, preferably about 80, percent of poly(vinyl alkylether) and about 90 to about 10, preferably 20, percent of cyclic esterpolymer, the percentages being based on the total weight of bothpolymers. When more than about percent cyclic ester polymer is blendedin the mixture, there is little if any tackiness and objects made fromsuch blends do not adhere to themselves even when pressed together atambient temperatures over extended periods. The presence of the cyclicester polymer also has an advantageous effect on the creep resistance.

Any suitable method of preparing the adhesive mixtures can be used. Forexample, the cyclic esther polymer can be fluxed on a two-roll mill orin a suitable mixer by heating to moderate temperatures, e.g., 60 C. ormore, and the poly(vinyl alkyl ether) can be added to it and mixingcontinued. After a substantially uniform blend has been obtained, themixture can be sheeted, extruded in the form of tapes or ropes, extrudedas a tubular film, extruded and pelletized in the conventional way,compression molded into pellets, tablets, plaques or other desiredshapes, or otherwise shaped or formed as desired.

In addition, powders or granules of the cyclic ester polymer can besprayed with melts, solutions or dispersion of the poly(vinyl alkylether) and dried, if necessary, to provide relatively dry powders orgranules. The cyclic ester polymer and poly(vinyl alkyl ether) can bedissolved in a common solvent and spread as a coating or film of mixedpolymers and dried. Any method for bringing the two polymers intointimate contact can be used.

Maximum bonding temperatures are, of course, determined by thedecomposition temperatures of the substrate or substrates and that ofthe adhesive composition. In substantially all instances in thisinvention, a wide margin of safety below these decompositiontemperatures is available because of the moderate temperature at whichthe adhesive composition is activated. The activation temperatures fallinto the range of 60 C. to 200 C. and represent the temperature at whichthe particular adhesive composition employed becomes molten or softenough to be deformed by pressure. Lower temperatures, e.g., as low as60 C. or 80 C. are suificient to cause bonding of the adhesivecomposition to itself, as for example, in its applications as heatshrinkable films and mending or repair tapes, described hereinafter.

The adhesive composition of cyclic ester polymer alone or mixed withpoly(vinyl alkyl ether) can be applied and bonded to the solid substratein any convenient manner. For example, a melt, solution or dispersion ofthe composition can be coated onto the substrate by spraying, brushing,rolling, extrusion, or flowing techniques and allowed to dry and/orcool. Alternatively, the adhesive composition in film form or powder,granular or pellet form can be spread on the substrate by any of theabovementioned techniques and heated, while being compressed onto thesubstrate, if desired, to soften or melt the composition and then cooledto form a tough, strong bond between it and the substrate. The thuscoated substrates are highly useful as heat bondable articles. Forexample, components to be assembled and fastened together into afinished structure can be manufactured and then coated in theabove-described manner at different locations, and then assembled andheat-bonded together in the desired structure at a common assemblylocation. Additionally articles designed for attachment to fixed orimmovable objects such as buildings or large objects such as vehicles orships can be coated as described above and transported and attached tothe object through the application of heat.

In bonding two or more substrates, as in the production of laminates,the second substrate is placed on the coating of the first substrateformed as described above. If the coating is dry and at ambienttemperature, the substrates are preferably pressed toward each other andheated to at least 60 C., preferably 80 C., to melt or soften theadhesive composition and then cooled to form a strong, tough bond. Ifdesired, the second substrate can be applied before drying and/orcooling of a freshly applied coating and pressed against the coatingwhich is then allowed to cool and dry to form a tough, strong bond.Laminates of two sheets of glass bonded to an interlayer of adhesivecomposition by the procedure disclosed herein are useful as shatterresistant glass.

When applied to cardboard, paper, Mylar film, polystyrene sheets andother packaging materials, the adhesive composition formsheat-activatable areas which can be formed in any patterns orconfiguration consistent with the desired package design. Thepoly(ethylene terephthalate) can be sol'vent precoated with thisadhesive polymer to be heat-activated and post sealed at a later orsubsequent bonding operation. Components or different areas of thepackage can thus be readily heatsealed using conventional techniques.Films of the adhesive compositions containing the cyclic ester polymeralone or mixed with the poly(vinyl alkyl ether) are also useful in thepackaging field as heat-shrinkable films. These films are first orientedby stretching them near room temperature. They can then be placed aroundthe article to be packaged or protected and heated to shrink and clingtightly to the article. In such instances, care should be taken to avoidadherence to the article either by selecting a low enough shrinkingtemperature or by limiting this use to articles which are not bonded bythe adhesive composition. By providing overlapping portion of the filmit can be caused to adhere to itself upon heating and thus form anightly clinging, sealed package.

In tape form, the adhesive compositions containing cyclic ester polymeralone or mixed with poly(vinyl alkyl ether) as described herein, areflexible and strong and have a wide range of uses. Such tapes can beused in the manufacture and repair of garments and other textile fabricsto form the seams, pleats, creases and other shapes in the garmentand/or to join two or more segments of the garment, or to repair rips ortears in garments. These tapes of cyclic ester polymer alone or mixedwith poly(vinyl alkyl ether) can also be oriented by stretching at roomtemperature to form heat shrinkable tapes which can be used to repairbroken glassware, broken wooden or plastic tool handles, and evenobjects which do not readily adhere to the adhesive compositions, byusing the methods described in Example 4 below, The tape can be wrappedaround the broken piece and heated or warmed to the activationtemperature and cooled to shrink and bond the tape to the broken pieceor to itself, if the tape has been overlapped on itself. In thoseinstances where there is little or no adhesion between the adhesivecomposition and the broken object, the heatshrinkable tape can betightly wound around the object and overlapped on itself and then heatedto the shrinking temperature, e.g., '60 to C. or higher, to seal thetape to itself and shrink it up tightly around the object. These tapesmay also have either woven or non-woven filaments of a higheruse-temperature polymer, e.g., poly(ethylene terephthalate) or fiberglass, to increase the joint strength.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following examples arepresented. Unless otherwise specified, all percentages and parts are byweight, all temperatures are on the centigrade scale, and all reducedviscosities are measured at a concentration of 0.2 gram of polymer inmilliliters of benzene at about 30 C. and Mylar designated poly(ethylene terephthalate).

EXAMPLE 1 A high molecular weight, noninitiated, substantial homopolymerof epsilon-caprolactone (PCL) having a reduced viscosity of 3.2 dl./gm.was blended with poly- (vinyl ethyl ether) (PVEE) having a specificgravity of approximately 0.968 and a reduced viscosity of about 50:05dl./gm. when measured in benzene at 20 C. and a concentration of about0.1 gm./ 100 ml. in various proportions. The homopolymer was prepared bydispersion polymerization in heptane of epsilon-caprolactone usingdibutylzinc catalyst and 'vinyl chloride-lauryl methacrylate copolymeras interfacial agent. The proportions of PCL and PVEE and the physicalproperties of each blend are given in Table I. The blends were made on atwo-roll mill at about 90 C. using conventional techniques. Blendabilitywas good at all ratios.

The blend containing 1 percent polycaprolactone was slightlytranslucent, a little more rigid than poly(vinyl ethyl ether). Thehigher PCL blends were noticeably more opaque, stifier, nontacky to thetouch, and did not block or adhere to themselves even after 24 hours ormore of pressure contact at room temperature. Based on the data in TableI, the creep resistance of the blends appears to be better than that ofpoly(vinyl ethyl ether) alone.

thickness of about 0.002 in. to form very useful heat shrinkable,adhesive films. For example, a broken glass vial was wrapped with a fewwindings of such a tape and then warmed. The film shrank about the glassupon warming and, after cooling to room temperature, adhered very wellto the glass and to itself within the laps of tape about the glass. Theresult was a well mended glass object. In another test, an ordinary woodcovered pencil was wrapped with the tape and warmed. Again the filmshrank about the pencil and, after cooling to room temperature, adheredwell to it to form a plastic coated object. When the pencil wassharpened, the coating, except for that portion removed in thesharpener, remained well adhered to the pencil.

Thus, such blends are useful in forming heat shrinkable films thatadhere to many substrates. In fact, such tapes TABLE I PCLIPVEE(percent) 0/100 l0/00 30/70 50/50 70/30 100/0 1% secant modulus, p.s.i.(stifiness) 64 300 1, 500 7, 800 17, 000 20,000 Tensile strength, p.s.i12 90 350 1, 300 3, 400 7, B00 Elongation, percent; 2, 700 900 040 1,200 1, 500 1, 200

EXAMPLE 2 are useful for mending objects even if they do not adhereTABLE II PCL/PVEE (percent) 0/100 10/90 30/70 50/50 70/30 1% seeantmodulus, p.s.l 64 70 460 1,000 13, 000 Tensile strength, p.s.l 12 26 6085 280 Elongation, percent 2, 700 2, 700 1, 050 160 25 These blends aresimilar in visual appearance and tack to the corresponding blendsdescribed in Table I, although their physical properties are lower htanthe corresponding blends of Example 1. It would appear that creepresistance of the blends as compared to PVEE alone is improved but notto the same degree as the corresponding blends of Example 1.

EXAMPLE 3 The blends described in Tables I and II containing 30 percentPC-L and 70 percent PVEE were molded into plaques about mils thick.Small pieces of these plaques were placed between glass microscopeslides, clamped, and warmed for about 10 minutes in an oven set atvarious temperatures. When these composite plaques were cooled to roomtemperature and tested for adhesion, the following results wereobtained:

Room temperature No adhesion.

40 C. No adhesion.

60 C. Good adhesion.

80 C. Very good adhesion.

In addition, when two small plaques of these blends were contacted witheach other under pressure for 48 hours at room temperature they did notadhere to each other.

These blends of PCL and PVEE are useful as heat sensitive adhesives thatdo not block at room temperature.

EXAMPLE 4 A blending containing 80 percent of a high molecular weight,noninitiated, substantial homopolymer of epsiloncaprolactone asdescribed in Example 1 and 20 percent of a high molecular weight poly(vinyl ethyl ether) (PVEE) described in Example 1 was prepared on atwo-roll mill at about 90 C. This blend was easily oriented by hand atroom temperature from a thickness of about 0.006 in. to a to the object.In these instances, the tape is looped around the object and constrainedfrom falling off. When warmed, the looped tape shrinks and bonds toitself, forming a tough, strong junction. For example, a meshpolyethylene basket that had broken was mended by looping the tape aboutthe broken meshwork of the basket. When warmed the tape shrank andeffected a good mend.

Another interesting use of tapes or films of the adhesive composition ofthis invention in unoriented form is their utility as heat sensitiveadhesives for bonding fabrics together (i.e., to form seams withoutsewing with thread) for a number of textile applications. One example isthe forming of seams in paper dresses and other fabrics of natural orsynthetic fibers or blends thereof.

A fiber glass-PCL laminate or a filled PCL laminate may be molded toform a three-dimensional cavity mold which can then be used to cast lowtemperature molding compositions such as plaster of paris and longcuring epoxies.

EXAMPLE 5 This example describes the use of a substantial homopolymer ofepsilon-caprolactone (PCL) alone of a blend of a substantial homopolymerof epison-caprolactone (PCL) and poly(vinyl ethyl ether) as adhesivesfor Mylar polyester (ethylene glycol terephthalate polyester) film. ThePCL used in both instances was the same as that used in Example 1. A 5percent methylene chloride solution of the high molecular weight,noninitiated POL and a methylene chloride solution containing fourpercent of the same PCL and one percent relatively low molecular weightpoly (vinyl ethyl ether) having a specific gravity of about 0.973 and areduced viscosity of about 03:0.1 when measured in benzene at 20 C. anda concentration of about 0.1 gm./ 100 ml. (/20 by weight polymer ratio)were prepared.

When each of these solutions was separately cast onto Mylar film, theyadhered extremely well. When two strips of such coated Mylar film weredried and placed together in a manner that the PCL-containing coatingswere in contact, warmed to about 60-70 C., pressed together by handpressure, and cooled to room temperature, excellent bonding took place.In fact, when one attempted to separate the laminate formed with PCLalone, the Mylar tore.

In the case of the blend, the bond was very good but the Mylar stripscould be separated without tearing the Mylar. Quick-drying solventsother than methylene chloride can be used. From the above, it is readilyapparent that the above-described solutions are good, heat scalableadhesives for Mylar and that they are quite useful in forming filmlaminates such as poly(vinyl chloride)/PCL/Mylar laminates or poly(vinylchloride)/PCL-poly(vinyl ethyl ether) Mylar laminates.

12 EXAMPLE 6 EXAMPLE 8 This example describes the uses of, respectively,a sub- The procedures of Example 6 were repeated using paper stantialhomopolymer of epsilon-caprolactone (PCL) as coated plasterboard insteadof plywood. In this instance described in Example 1 and a substantialhomopolymer of r also the substrate failed and the polymer did not. 2-leto-l,4 -dioxane (PKD) made by a dispersion polym- EXAMPLE 9 erizationin heptane using 3.0% poly(v1nyl stearate) as intcrfacial agent,tri(isobutyl)aluminum catalyst (percent everal Solutions were preparedby dissolving two subbased on weight of caprol-actone) and having areduced stantial homopolymers of epsilon-caprolactone of difierentviscosity of 0.84 in o-cresol at 30 C. as adhesives for molecularweights in Z-IlitTOPI'OPaIIe 111 the respective plywood, Plywood strips4" X 1" X were used, The 10 amounts shown in Table III below. A dye, DuP0111; PCL in powdered form was spread on one of the strips VictoriaPure Blue B0 was added in the amounts shown near the end thereof andanother strip was placed over the t0 the W0 Cyclic s e p lym r SOIHHOIISShOWH' A180, polymer. The strips were then clamped and heated in antitanium dioxide pigment in the amount shown was added oven respectivelyat 60 C., 80 C. and 100 C. for about to the solutions designated inTable III. The cyclic ester 10 minutes. After cooling to roomtemperature the clamps p ymers used were made by dispersionpolymerization were removed and an attempt was made to separate theusing vinyl chloride/lauryl methacrylate copolymers as strips by hand.The strips heated at 60 C. were easily in erf ci l agent an n ani ni cys h as tnpulled apart. The strips heated at 80 C. and at 100 C. (lsobuybalumlnum. The reduced viscosi y of one polywere bonded very well andthe wood broke rather than 1116f was and the reduced S 'EY f t thepolymeric bond when separation was attempted. other polymer (PCL-Z) was1.34. i

Two coats of a five percent methylene chloride solution Ink filmproperties of each result ng ink were deter- Of the PCL were placed ontwo plywood strips near the mined by coating each ink on the varioussubstrates listed ends thereof. When the coatings became tacky byevapoin the table by a roller coater and these properties are ration ofsolvent, the strips were clamped together, heated also listed in TableIII.

TABLE III Dye inks Pigmented inks Ink Properties PGL-l POL-2 PCL-l POL-1POL-2 POL-2 t 0. 1.34 (0.6) (0.6) (1.34) (1.34).- gtglggli ilsfff fljfifi iii 0 fitment lLO percent.-- 32.2 perccnt 32.8 percent"...19.8perccnt..... 19;; unscr- Dye or pigment percent of total solids 10 110 1 50 2 61 1 50 2 61 h /I pmllemes: G d Good Fair Fair Fair I FairF1aiiift$iit n enentiiji: Easiest-.1113: EXCala'i JLI: e00a..' Exantral-.1311: Good. Adhlclsion t 1] h d G0od+ Poor Poor Poor Poor 'ma nNilz igzel lulisse gated cellophane d0 Excellent Excellent- Excellent;Excellent Excellent. Polyvinylidene chloride coated cell phane MylarGood Shellac washed a1. foil Excellent Glassine paper "d do Good Castcoated paper Good Poor... Gloss Excellent Excellent G0od+ Boiling waterresistance Poor oor Excellent Ice water resistance Excellent ExcellBlock resistance do o Excellent Excellent 1 DuPont Victoria Pure BlueBO. 2 TiO in an oven respectively at 60 C., 80 C. and 100 C. for EXAMPLE10 about 10 minutes, and cooled to room temperature. In all Four cyclicester polymers were tested in this casesi, 1ye ry good adhesion resultedand, in each 035% ample as adhesives for various substrates. Woo 4rather than the PCL A cyclic ester polymer, hereinafter designatedPOL-3,

fil Sum g PKD was used Thls Polymer has was prepared by bulkpolymerization of epsilon-caproa lgher meltmg Pomt than, PCL and thusShould h a lactone in the presence of 650 p.p.m. water and 0.2% greaterservice range. In this case the clamped specimens Stannous octoate(parts and percentages based on Weight Were.heated to 130 about 15mmutes The Polym,er of caprolactone) at a temperature of 150 C. for aperiod prgvldes Very good of the Plywood Once agam, of 3 to 5 hours.After a period of about 2 hours, the w en tested the wood failed ratherthan the PKD polymtemperature was increased to to complete the ericbond.

1 h polymerization at a decreased melt viscosity. The poly exanpustraies t e use of the adheswe meric product had a reduced viscosity of0.65. ROSltlOl'iS 0 this invention for plywood. These composi- A cyclicester Polymer designated PCL 4 was prepared trons aso can be used tobond Mylar to plywood and in the Same manner as PCL 3 except that 406p'p.m asapamt for Plywood water was used instead of 650 p.p.m. and theresulting product had a reduced viscosity of 0.98.

A cyclic ester polymer designated PCL-S was prepared by dispersionpolymerization in heptane of epsilon-caprolactone using about 5%poly(vinyl stearate) as inter- EXAMPLE 7 Small amounts of various dyes,namely, Du Pont Rhodamine B, Du Pont Brilliant Green, and Du PontVictoria Blue, were added to methylene chloride solutions containingfive percent of the substantial homopolymer of epsilon-caprolactone asdescribed in Example 1 to form ink compositions. These inks were used towrite in tages based on weight of caprolactone) at about 90 C. for aperiod of about 1 hour to about 4 hours. The resulting product wasextruded and pelletized to provide a polymer designated PCL-S having areduced viscosity color on 3M brand, Type 127, Mylar, projection posiof152 tives. After drying, it was found that the inks had very Films of pc4 and 5 are prepared by good adhesion to the substrate. When the slidewas PIO- co npression molding the respective polymer in a press iectcd,the Writing Was Projected in color- Such p to obtain a film ranging inthickness from 10 to 20 mils. iti n a us ul as s t allow, for p alecturer The resulting films are placed between two substrates to towrite or to mark in color on various substrates and be adhered asidentified in part B of Table IV. These allow color printing on a widevariety of substrates. laminates are bonded at the indicatedtemperatures, pres facial agent and 0.3% tri(isobutyl)aluminum (percen-13 14 sures and periods of time shown in Table IV and the paper stockand crease and folding resistance of the coated adhesion values alsoshown there are obtained. stock is excellent especially for the highermolecular The adhesion values are obtained according to a modiweightpolymers. fication of test ASTM-D-1876-61T wherein the crossheadThereafter, a film of poly(ethylene terephthalate) is speed of thetesting device is changed to 2" per minute. pressed onto the coatedpaper stock and heated (about In these examples the testing device isattached to the 120 C.) to form a laminate in which the chipboardsubstrates with the PCL as the inner core. Thus, a peel paper stockadheres very well to the poly(ethylene tervalue or strength of adhesionof substrate to PCL to ephthalate) film upon cooling to roomtemperature. In substrate at essentially a 90 angle is obtained.addition, a sheet of polystyrene is pressed onto the coated For thosesubstrates which were too rigid to provide a stock and heated (about 120C.) to laminate it to the testing angle 0 086 o during the adhesivetesting stock. The polystyrene sheet also adheres very well to thestudy, a bond between a P0111011 Of the PCL film and a paper stock uponcooling to room temperature, single layer of rigid substrate is formed,under conditions S b i ll i il results are b i d as i respecindicated inTable P A, thus Providing an 1111- tively Examples 3 through 7 and 9through 13 when the bonded tab of PCL. In this part of the st dy, h P6615 substantial homopolymers of and copolymers of two or Val s aConveniently Obtained y attaching the rigid more of the following cyclicesters are respectively sub- Sllbstrate to one P 0f the testing deviceand attaching stituted for the epsilon-caprolactone polymer in each ofthe flexible and unbonded PCL tab to the other part of these examples;the testing device. The testing of these PCL-substrate bonds is thenelfected at a peel angle of 90 formed by delta-valerolactone, the PCLtab. The results are listed in part A of Table IV. zeta-enantholactone,Where the substrates are flexible as in part B of Tableeta-eaprylolactone,

IV each substrate is attached to the testing device asexmonomethyl-delta-valerolactone, plained above.monohexyl-delta-valerolactone,

TABLE IV Bonding parameters Adhesion Time, T C. P.s.i. min. PCL-3 POL-4PCL-5 Subtrate A: Impact polystyrene 1 150 40 2 ExceAcrylonitrilebutadienestyrene copolymer 2 150 80 2 do lixmuontPolyurethane 3 185 20 2 n Fair Glassreinforced epoxy board..- 150 20 2 nEwnuonf Wood-Douglas fir plywood 180 20 3 Excellent (wood failure).Polystyrene 4 180 20 2 Exc ellent Glass 200 1 15 do Subtrate B:

Poly(ethylene terephthalate) (2 mils) 195 40 1 Poor Good Excellent,Paperboard stock 100 10 1 Excellent Al metal 10 mil (al-al) 180 15 3Poor Fair A styrene grafted pclybutadiene copolymer which iscommercially available containing about 9% of the polybutadienecomponent, possessing a specific gravity of 1.04 (ASTMD792), a softeningpoont of 195 F. (ASTM-D1525) and possessing an Izod impact strength at73 F. of 1.40 (ASTM-D256).

2 A thermoplastic prepared by grafting a mixture of acrylonitrile andstyrene (about 30 parts acrylonitrile and 70 parts styrene) onpolybutadiene (or 1 A thermoplastic prepared by grafting a mixture ofacrylonitrile and styrene (about 30 parts acrylonitrile and 70 partsstyrene) on polybutadiene an acrylonitrilei outadiene rubber) to yield aproduct with an acrylonitrile content in the range of 20 to The materialused possesses a specific gravity of 1.05, an Izod impact strength of2.9 (ASTMD256) and a heat distortion temperature at 264 p.s.i. of 185 F.(AS'IM-D648).

3 A commercially available product prepared by the reaction of a lowmolecular weight poly(butanediol adipate) with molecular weight in therange of 2,000 to 3,000 with a diisocyanate to yield a high molecularweight (35,00050,000) polyurethane. The diisocyanate is diphenylmethanediisocyanate.

The polymer possesses a specific gravity of 1.23.

4 An unfilled (transparent) homopolymer of polystyrene prepared via bulkpolymerization to yield a polymer with a molecular weight in excess of60,000 and a specific gravity of 1.05.

EMMPLE 11 tri-n-propyl-epsilon-caprolactone,

thoxy-delta-valerolactone Employing the procedure of Example 10,poly(ethylntonome ene terephthalate) (Mylar) film is bonded to each ofgizzg i ig 'lz igg z nd styrene film, paperboard and a film ofacrylonitrile-buta- 3. eps n p t diene-styrene copolymer using, inseparate instances, mo 180p mp oxy'ep S apro ac PCL-3, PCL-4 and PCL-5films-sandwiched between the What is claimed is:

Mylar film and each of the other above-named films. The 1. An adhesivecomposition comprising about 10 to resulting composite articles areheated to about 195 C. about 90 Weight percent of poly(vinyl alkylether) and with the exception of the paperboard composite article about90 to about 10 weight percent of a cyclic ester which is heated to about100 C. While at this temperapolymer, based on the total weight ofpoly(vinyl alkyl ture the composite articles are pressed together undera ether) and cyclic ester polymer, having a reduced vispressure of about80 p.s.i. for about 2 minutes. Each comcosity of about 0.3 to about 15and having at least a major posite article shows excellent adhesion ofalt layers, in amount of recurring structural units of the formula:every instance. (I) R R 0 EXAMPLE 12 1;

C(A).-C A film of polyurethane and a film of acrylonitrile-buta- L Jdiene-styrene copolymers are bonded together by films wh I erem each R,individually, is selected from the class of PCL PCL l and PC 5 m themanner desmbed consisting of hydrogen, alkyl, halo, and alkoxy; A is thein Example 10 by sandwiching of the PCL films between the other twofilms mentioned. The resulting composite gg l g hf 5 g 21 :3 :5 figgfigf articles are pressed together under a pressure of about 80 a VlSOSthat (a) the sum of x+y+z is at least 4 and not p.s.1. at a temperatureof 150 C. for about 2 minutes. All composite articles exhibit excellentadhesion of all f fgff f gg g gg ifig g gg $2 gl g ggzn flo zs t r zlayers EXAMPLE 13 ceed 3; and up to a minor molar amount of recurringstructural units of the formula:

Chipboard paper stock is coated with a hot melt (about (II) R R1 120 C.)of, respectively, PCL-3, PCL-4 and PCL-5 as I identified in Example 10and allowed to cool. The result- T a f ing PCL films all ShOW goodadhesion to the chipboard H H 15 wherein each R is selected from theclass consisting of, individually, hydrogen, alkyl, cycloalkyl, aryl,and chloroalkyl, and, together with the ethylene moiety of theoxyethylene chain of unit II, a saturated cycloaliphati'c hydrocarbonring having 4 to 8 carbon atoms.

2. Adhesive composition as claimed in claim 1 wherein said po1y(vinylalkyl ether) is poly(viny1 ethyl ether).

3. Adhesive composition as claimed in claim 1 wherein said cyclic esterpolymer is a substantial homopolymer of epsilon-caprolactone.

4. Adhesive composition as claimed in claim 1 wherein said cyclic esterpolymer is a butyl carbitil initiated epsilon-caprolactone polymer.

5. Adhesive composition as claimed in claim 1 where- References CitedUNITED STATES PATENTS 2,647,100 7/1953 Salditt 260874 2,697,084 12/1954Eger 260--874 3,169,945 2/ 1965 Hostettler et a1. 260874 3,231,5541/1966 Kern 260874 3,497,574 2/ 1970 Press 260874 SAMUEL H. BLECH,Primary Examiner U.S. Cl. X.R.

117l61UB, 161 UC, 161 K; 156327; l6ll82, 183, 184, 190, 203, 208, 226,227, 231, 242, 247, 248, 250,

in said cyclic ester polymer is a substantial homopolymer 15 52, 253; 2637 899 of 2-keto-1,4-dioxane.

